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E39 (1997 - 2003) The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

You'll have to go thru one of the four drive cycles below for whichever "Evaluated" part of the emissions system the fuel filler cap falls under. If after going thru the drive cycle, the issue no longer exists...then the light will go off. If the problem remains...then the light will stay illuminated:

There is an 0 ring on the cap that seals up with the tank--I had my light coming on from time to time a few years back. I made the fix that still works for me by doing the following. Carefully remove the 0 ring from the cap. There is a cupped outer edge of the ring that I used black permatex gasket silicone--sensor safe by the way. I carfully filled that whole outer edge of the 0 ring with the permatex --then let it set up over night.
Put the 0 ring back on the cap the next day--cleared the code with my code scanner--and it's never been on again. Over 4 years now with that fix.

Yep--you can buy a new 0 ring--I've even looked the part # up a time or tow--but with the permatex fix
the original 0 ring is strengthened and works well enough for me ---so far LOL---probably be the next thing to go

I just picked up a new (16 11 1 184 731) Fuel Tank Cap.
This new one has done away w/ the oring. THere's now a large rubber donut gasket instead of the o-ring. & cap comes with a 4" tether line to keep it captive to the door lid.

I haven't started the car yet, but I checked the codes and there were none before I did this so, starting from that point, l'll let you know how many miles it takes for whatever error to occur (I expect what QSilver7 said to be the case ... as he is infallible ... but let's see).

Stay tuned ...

Quote:

Originally Posted by AnotherGeezer

Many go whole hog GT1 (as I may someday)

I too, desire to "go whole hog" and get one of the "fancy schmancy" diagnostic scanners. Some day. Round tuit. Job. And all that.

My gas cap would not stay in the normal locked position when the cap was tight and when you normally turn beyond tight it will make a ratcheting click sound. When my cap failed it would not stay locked in the tight position and literally reverse itself a bit not keeping the lock or seal.

Pulled into our regular more than friendly Toyota dealer who scanned my BMW for free then within a minute diagnosed the leak problem described above for free. Amazing how great service can attract customers for life.

I haven't started the car yet, but I checked the codes and there were none before I did this so, starting from that point, l'll let you know how many miles it takes for whatever error to occur (I expect what QSilver7 to be the case ... but let's see).

Stay tuned ...

"ABS
I too, desire to "go whole hog" and get one of the "fancy schmancy" diagnostic scanners. Some day. Round tuit. Job. And all that.

Bluebee, one of reasons I signed up for this forum is your dogged determination to divine some kind of logic from what can seem a bewildering array of causes and effects, as exemplified in this thread and the "ABS-Traction Control" conundrum. Every time I read one of these threads, I think, "Thank God someone has the energy to pursue this."

I haven't started the car yet, but I checked the codes and there were none before I did this so, starting from that point, l'll let you know how many miles it takes for whatever error to occur (I expect what QSilver7 said to be the case ... as he is infallible ... but let's see).

Stay tuned ...

Blue...before the SES/CEL will illuminate...the system will need to set TWO fault codes. The first one can be pulled up as a pending code (if you hook up your scanner & you're drive cycle has been one that tests the EVAP emissions). Refer to the chart below...look at the first section on the left...it describes when the EVAP system is checked (cold engine start & idle for 2 min & 10 sec).

Again, after the second fault has been recorded...the light should illuminate. See the 2nd paragraph in the 3rd bullet in info below.

An OBD II drive cycle is not just turning the ignition key on and off or starting the engine. A drive cycle requires starting a cold engine and driving the vehicle until the engine reaches normal operating temperature. The next drive cycle doesn't begin until the engine has been shut off, allowed to cool back down and is restarted again.

Given that, I'll need to wait until some cold temperature is reached before resuming the test for the team.

Also note that this gas-cap test may require an 8 hour interlude!

Quote:

on some vehicles, the EVAP monitor won't run unless the vehicle has not been run for eight hours

Katie O'Malley! They sure do make it hard to test what code occurs when your gas cap is off the vehicle!